Study data
But on June 15, FDA advisers had to consider an EUA application for which the data did not make as strong a case for the vaccine’s benefit among younger patients.
Pfizer presented what the FDA called a “preliminary descriptive analysis” of vaccine efficacy among participants in Study C4591007 who received three study vaccinations, following accrual of 10 total confirmed COVID-19 cases occurring at least 7 days after the third dose.
Looking at results for study participants ages 6 to 23 months of age, there was one case in the group that got the Pfizer-BioNTech shot and two in the placebo group, pegged as a 75.6% vaccine efficacy rate -- but one with caveats to the small numbers of cases. The 95% confidence interval for this vaccine efficacy rate was reported as-369.1% to 99.6% according to the FDA staff review.
For participants 2-4 years of age with and without evidence of prior SARS-CoV-
2 infection, there were two cases in the group that got the shot and five in the placebo group showing a vaccine efficacy rate of 82.4%, with a 95% confidence interval estimated ranging between -7.6% and 98.3%. For the combined analysis of both age groups, the efficacy rate was estimated at 80.4%, with a 95% confidence interval of 14.1% and 96.7%.
Doran Fink, MD, PhD, a top official in the FDA’s vaccines division, noted that the current EUA application for expanded pediatric use involved “some very preliminary” results that involved “a small number of cases and limited follow up time.”
But he stressed that the evidence gathered to date for the Pifzer application for use of its COVID shot in infants and young children met the threshold for conditional clearance during a crisis.
“We do feel very confident that the evidentiary standard for benefit for an EUA has been met here,” but added that more data would be needed to address questions about the efficacy of the vaccine beyond a third dose and whether an additional dose may be needed.
Pfizer also used a comparison known as “immunobridging” in support of the application. This looked at SARS- CoV-2 50% neutralizing antibody titers for the children in the age group covered by the EUA application and compared them to a randomly selected subset of 16-25-year-old participants in another study,
Key data for the pending Moderna EUA for use of its shot in infants and young children came from study P204. In it, Moderna found 51 cases of COVID among 1,511 children ages 6 months to 23 months who got the vaccines, versus 34 cases among 513 children who received a placebo, according to an FDA staff review.
That resulted in a vaccine efficacy rate pegged at 50.6%, with a 95% confidence interval of 21.4% to 68.6%.
Looking at the children ages 2 to 5 years in the P204 study, there were 119 cases out of 2,594 participants who got the shot, versus 61 cases of 858 in the placebo arm, or 7.1%. That translated to a 36.8% vaccine efficacy rate, with a confidence interval 12.5% to 54.0%.
Panelist Jay Portnoy, MD, of Children’s Mercy Hospital in Kansas City said all of the pediatricians he knows are waiting for the FDA to authorize the new uses of these vaccines in infants and young children.
“The death rate from COVID in young children may not be extremely high, but it’s absolutely terrifying to parents to have their child be sick, have to go to the hospital or even go to the emergency room or their primary care doctor because they’re sick and having trouble breathing,” said Dr. Portnoy, who served as the panel’s consumer representative.
A version of this article first appeared on WebMD.com.
This article was updated on 6/16/22.